JPH0617232B2 - Method for producing hydrated spherical titanium oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydrated spherical titanium oxide used as a raw material for producing crystalline spherical titanium oxide used as a raw material for pigments, fine ceramics, etc. It relates to a manufacturing method.

(Prior Art) Conventionally, as a method for producing this type of hydrated spherical titanium oxide, an alkoxide utilizing hydrolysis of titanium alkoxide such as Ti (OC ₃ H ₇ ) ₄ · Ti (OC ₂ H ₅ ) ₄ has been used. A method is known, and by heat-treating hydrated spherical titanium oxide having a submicron monodispersion obtained by such an alkoxide method, highly crystalline spherical titanium oxide having a submicron monodispersion can be obtained.

(Problems to be Solved by the Invention) In the case of the conventional alkoxide method, hydrated spherical titanium oxide cannot be obtained without complicated controlled hydrolysis of titanium alkoxide in a dilute concentration, and the production is complicated. In addition, the production efficiency is low, and since the liquid viscosity of titanium alkoxide is high, it is necessary to use an organic solvent such as isopropyl alcohol and ethyl alcohol. Further, since titanium alkoxide is expensive, the production cost is high.

(Means for Solving Problems) An object of the present invention is to provide a method for producing a hydrated spherical titanium oxide in which the above-mentioned inconvenience is eliminated, and the present invention has a pH adjusted to 4 or more. In an aqueous solution, hydrogen peroxide is allowed to act on the soluble titanium compound to form a titanyl ion hydrogen peroxide complex, and the solution containing the complex is left at room temperature or heated.

The pH of the aqueous solution should be adjusted to 4 or higher because if the pH is less than 4, the titanyl ion hydrogen peroxide complex will decompose at room temperature even if hydrogen peroxide acts on the soluble titanium compound, and titanium hydroxide gel will precipitate. This is because it will end up. The pH is stabilized as it moves to the alkali side, and a high-concentration titanyl ion hydrogen peroxide complex can be obtained. To adjust the pH of the aqueous solution, an alkali such as aqueous ammonia is used.

As hydrogen peroxide, commercially available hydrogen peroxide solution is generally used.

As the soluble titanium compound, for example, titanium compounds such as titanium trichloride, titanium tetrachloride, titanyl sulfate, titanyl nitrate and titanium hydroxide are used. In particular, when it is desired to obtain highly pure hydrated spherical titanium oxide, the titanium compound is hydrolyzed in advance to form hydrous titanium hydroxide, and the anions are sufficiently removed by washing with water, etc. The hydrogen peroxide solution may be allowed to act on the.

The titanyl ion hydrogen peroxide complex obtained by acting the hydrogen peroxide on the soluble titanium compound produces hydrated spherical titanium oxide even when left standing at room temperature for a long time,
Hydrated spherical titanium oxide is produced in a short time if a moderate heating treatment is applied. If necessary, the seed of ultrafine particles or some mechanical impact is applied to start the precipitation reaction of hydrated spherical titanium oxide. The precipitation reaction once started continues without stopping halfway until all hydrogen peroxide complexes are decomposed. Since the solubility of the hydrated spherical titanium oxide produced is extremely small, the production rate is 100%. Incidentally, it is considered that the precipitated hydrated titanium oxide becomes spherical because of the homogeneous nucleation reaction mechanism. The obtained hydrated spherical titanium oxide is washed with water as necessary, separated and dried.

The obtained hydrated spherical titanium oxide had 400 to 800
By subjecting to a heat treatment at about ℃, anatase-type highly crystalline spherical titanium oxide close to submicron monodisperse can be obtained.

(Examples) Next, specific examples of the method for producing a hydrated spherical titanium oxide of the present invention will be described together with comparative examples.

Example 185 ml of pure water was added to 15 ml of an aqueous solution of titanium tetrachloride of about 0.4 M (manufactured by Osaka Titanium Manufacturing Co., Ltd.) to prepare 200 ml of an aqueous solution of titanium tetrachloride of about 0.3 M. Aqueous hydrogen peroxide solution (Wako Chemical Co., Ltd., H ₂ O ₂ concentration 30
wt%) 17 ml was added to obtain a blackish brown liquid. Furthermore, 18 ml of a reagent grade ammonia water (manufactured by Wako Chemical Co., Ltd., ammonia concentration 28-30 wt%) was added to this solution to obtain a yellow transparent aqueous solution. The pH at this time was 10. This aqueous solution was kept in a water bath at 50 ° C. for 10 minutes to precipitate hydrated spherical titanium oxide fine particles. When the deposited particles were observed by a transmission electron microscope, it was confirmed that spherical particles having submicron monodisperse, similar to those obtained by the conventional alkoxide method, were obtained. Next, the precipitated fine particles were thoroughly washed with pure water, separated from the mother liquor by a centrifugal separator, and dried at room temperature. After drying, the deposited fine particles were subjected to thermogravimetric analysis and differential thermal analysis. The heating loss curve and the differential heat curve obtained are shown as curves A and A'in FIG. 1, respectively. The obtained dry powder of hydrated spherical titanium oxide was calcined at 400 ° C. for 2 hours to obtain crystalline spherical titanium oxide. The obtained crystalline spherical titanium oxide was subjected to X-ray diffraction, and its X-ray pattern is shown in FIG.

Comparative Example In the same manner as in the above Example, 200 ml of an aqueous solution of titanium tetrachloride of about 0.3 M was prepared, and 182 ml of pure water was added to 18 ml of ammonia water of the same reagent grade as described above to prepare 200 ml of diluted ammonia water. The prepared adjusted ammonia water was gradually added dropwise to the above titanium tetrachloride aqueous solution with sufficient stirring to precipitate titanium hydroxide. When the deposited particles were observed with a transmission electron microscope, they were not spherical particles but gel-like deposits. Next, the gel precipitate was thoroughly washed with pure water, separated from the mother liquor by a centrifuge, and dried at room temperature. After drying, thermal analysis was carried out in the same manner as in the above example, and the resulting heating loss curve and differential thermal curve are shown as curves B and B'in FIG. 3, respectively. In addition, next, the obtained dry powder was calcined at 500 ° C. for 2 hours. The obtained calcined product was subjected to X-ray diffraction, and its X-ray diffraction pattern is shown in FIG.

The heating loss curve and the differential thermal curve obtained by thermal analysis of the dried product of hydrated spherical titanium oxide obtained by hydrolysis of titanium alkoxide by the conventional method are shown as curves C and C'in FIG. 5, respectively. Indicated. Further, FIG. 6 shows the X-ray diffraction pattern of crystalline spherical titanium oxide obtained by calcining the dried product at 430 ° C. for 2 hours.

The hydrated spherical titanium oxides obtained in the examples from the above-mentioned examples, comparative examples and respective heating loss curves, differential thermal curves and X-ray diffraction diagrams of the alkoxide method shown in FIGS. However, by heat treatment at a lower temperature than that of Comparative Example, highly crystalline anatase titanium oxide equivalent to crystalline spherical titanium oxide obtained by calcination of hydrated spherical titanium oxide by the conventional alkoxide method can be obtained. It was confirmed.

(Effect of the Invention) As described above, according to the method for producing a hydrated spherical titanium oxide of the present invention, in an aqueous solution whose pH is adjusted to 4 or more,
Hydrogen peroxide is allowed to act on the soluble titanium compound to form a titanyl ion hydrogen peroxide complex, and the solution containing the complex is allowed to stand at room temperature or heated, so that it is much simpler than the conventional alkoxide method. It is possible to produce hydrated spherical titanium oxide close to submicron monodispersion with high production efficiency and at low cost. Also, the obtained hydrated spherical titanium oxide is close to submicron monodisperse like the conventional alkoxide method. It has effects such as obtaining highly crystalline spherical titanium oxide.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 3, and FIG. 5 are thermal analysis characteristic diagrams of deposits obtained by Examples of the present invention, Comparative Examples, and Conventional Examples, respectively, and FIG. FIG. 4 and FIG. 6 are X-ray diffraction patterns of the calcined product of each precipitate, respectively.

Claims (1)

[Claims] 1. A hydrogen peroxide is allowed to act on a soluble titanium compound to form a titanyl ion hydrogen peroxide complex in an aqueous solution whose pH is adjusted to 4 or more, and the solution containing the complex is left at room temperature or heated. A process for producing a hydrated spherical titanium oxide comprising: